The use of soap dispensers is now widespread, as the awareness for the need of good hand hygiene practices grows. In the past, numerous types of dispensing systems have been known, including wall mount, counter mount, under the counter, and the like. Typically, these soap dispensers have been of a nature to dispense a predetermined amount of liquid soap upon actuation. Over the past decade or so, interest has grown in foam soap dispensers, in which the soap is dispensed in the form of a foam, comprising a uniform mixture of air and liquid soap to form a substantially homogenous foam.
While various foam soap generators and pumps have previously been known, they have typically been of a complex nature, and have often sacrificed reliability and operability for cost. Typical pumps have often included concentric or axially aligned air and liquid chambers and complex valving methodologies to achieve the desired foam generation and dispensing. In general, previously known systems have also failed to produce a high quality foam of uniform consistency, have not been given to implementation in various orientations, have been difficult to manufacture and assemble, and have generally not been given to ease of adaptability to the dispensing of various doses of soap.
Indeed, in the prior art, foam has been generated by activating two commercially available pumps tied together to deliver air and liquid into a foam producing cartridge. Others have attempted to cylindrically stack liquid and air pumps to deliver a combination of the two, in the form of a prefoam or otherwise, to a foam generating stage. Other prior art has employed the use of ball and spring valves that typically only work in one orientation, requiring significant design change for adaptation for use in another orientation. The prior art has also sought to accommodate the dispensing of various doses of soap by changing either the piston size or the stroke thereof.